The amniotic membrane (AM) is an avascular membranous sac that is filled with amniotic fluid surrounding the fetus. The AM, like the placenta, is derived from the epiblast formed during development of the fertilized egg. The AM forms the innermost membrane surrounding the fetus in the amniotic cavity. In placental mammals, the umbilical cord (i.e., the funiculus umbilicalis) connects the developing fetus to the placenta. The umbilical cord is made up of amniotic membrane (UCAM) and Wharton's Jelly. The amniotic membrane forms the outer layer of the umbilical cord. The UCAM functions to regulate the fluid pressure within the UC. Wharton's Jelly is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides (hyaluronic acid and chondroitin sulfate). It also contains some fibroblasts and macrophages. The umbilical cord further comprises two arteries (the umbilical arteries) and one vein (the umbilical vein), buried within the Wharton's Jelly.